of fish were lost during the experimental period. On September 3 the ex- 

 periment was discontinued due to the presence of anemia in this lot of 

 fish. 



Throu^out the experimental period from July 9 to September 3 the loss 

 of the control lot, fed 100 percent beef liver, amounted to U percent of 

 the initial number of fish. There were no symptoms of anemia in this group 

 when the experiment was concluded. 



From this phase of the experimental work it was concluded that both 

 the acetone-extracted salmon viscera meal and the low-temperature-dried 

 salmon viscera meal were deficient in adequate amounts of thiamine to meet 

 the requirements of blueback salmon. It was apparent also that the acetone 

 extraction removed more of the available t^iiamine than did the drying pro- 

 cess. If this were not true the 3;,7nptom3 of a thiamine deficiency should 

 have appeared concurrently in both groups and not with a 12-day lag period 

 between the two diets. The results of the thiamine assays of these meals 

 will be included in a later report. 



The addition of thiamine hydrochloride to the diet appeared to be suc- 

 cessful in alleviating the deficiency although the treatment was hampered 

 by the loss of appetite in the fish wldch is one of the symptoms of the 

 deficiency. The survival of some of the stock of affected fish for 30 days 

 after the symptoms first appeared is clear-cut evidence to supoort this 

 conclusion. 



Acetone- extracted salmon viscera meal does not appear to contain the 

 anti-anemia factors although the picture is partially obscured by the 

 thiamine deficiency. The presence of an anemia and this thiamine deficiency 

 are not necessarily associated. Erythrocyte counts, wfiich were made on 

 moribund fish showing the typical retracted head, deflated flanks, and 

 nervous spasms associated with a thiamine deficiency, disclosed an average 

 normal count of 1,200,000 per cubic millimeter of blood. These counts were 

 taken at the time the thiamine deficiency first made its appearance. How- 

 ever, as the experiment progressed, examination of the fish for gin colora- 

 tion revealed a gradual diminution of the red coloration until, when the 

 experiment was concluded on September 3, all of the remaining fish showed 

 positive evidence of an anemia. A significant fact is that the course 

 of this development was closely paralleled in the fish fed the low-temperature- 

 dried salmon viscera meal which does not contain the anti-anemia factors. 

 However, the loss of the desire to feed associated with the tHamine de- 

 ficiency may have been responsible for the development of the anemia. This 

 experiment should be repeated using a thiamine supplement throughout its 

 course. 



Growth evaluations 



The growth evaluation experiments differed from the survival experi- 

 ments in that each of the paired troughs on a single diet contained 1,000 

 grams of fish or 715 fish per diet. The fish were retained in the standard 

 Leavenworth deep troughs and the full length of 16 feet was utilized as 

 contrasted to the survival expo-iments in which but one-quarter of the length 



54 



